Question

$|?| = 0$
cos(A+B) -sin(A+B) cos2B
sinA. cosA. sinB
-cosA. sinA. cosB

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Answer 1

Answer:

Cos(A+B)cos(A−B)≡(cosAcosB−sinAsinB)(cosAcosB+sinAsinB)≡cos2Acos2B−sin2Asin2B≡cos2A(1−sin2B)−(1−cos2A)sin2B≡cos2A−cos2Asin2B−sin2B+cos2Asin2B≡cos2A−sin2B

Answer 2

Answer:

From which class is this and subject ????